A rare poorly understood illness among some cannabis users is generating significant controversy. Cannabinoid hyperemesis syndrome (CHS), as rare as it is, sometimes occurs among heavy users and is characterized by severe abdominal pain and vomiting. Taking hot showers is one-way patients with this condition ease their suffering.

While those who always seem eager to latch onto any anti-marijuana information are insisting that heavy, long-term marijuana use is the sole cause of CHS, some experts are saying there must be another missing piece to the puzzle. Given the non-toxic nature of cannabis, it’s puzzling that a substance used as an anti-nausea measure for decades would actually cause vomiting.

UK, London, Accident & Emergency entrance at University College Hospital, University College Hospital (UCH), was founded in 1834, eight years after University College London, in order to provide clinical training for the medical classes of the University after a refusal by the governors of the Middlesex Hospital to allow UCL students access to that hospital’s wards. (Photo by Universal Images Group via Getty Images)

Since 2009, emergency room diagnoses for CHS in two Colorado hospitals nearly doubled. But that may not be as dire as it sounds; many physicians have just become aware of the diagnosis in the past few years.

Now that the word has gotten out among doctors, it’s a two-edged sword. On the one hand, it’s fortunate that doctors can allay the fears of patients who aren’t sure quite what is happening to them. On the other ( and I have seen this happen multiple times among friends) some anti-pot physicians can very dismissively ascribe symptoms to CHS when, in fact, they are indicative of other serious medical problems completely unrelated to CHS.

“We have patients being refused treatment for actual flu vomiting in Denver emergency rooms because they said ‘yes’ when asked if they use cannabis,” said Martha Montemayor, clinical nurse consultant and director of Cannabis Clinicians Colorado.

These doctors, of course, would point to the obvious: that CHS symptoms usually disappear after a few weeks of abstinence. But this would be equally true, of course, if some impurity, whether pesticide or chemical fertilizer were present in the weed.

Cannabinoid Hyperemesis Syndrome (CHS) was first recognized in 2004.

The earliest study which focused on CHS was in 2004 when Australian researchers noticed patients experiencing cyclical vomiting symptoms. They found the common factor of cannabis use among the patients. Seven out of 10 subjects who abstained from cannabis resolved their cyclical vomiting; the other three patients refused to abstain, and their symptoms continued.

Now that the symptoms are becoming more well known among physicians, patients who would formerly have been diagnosed as having cyclical vomiting syndrome (CVS) are now being diagnosed as suffering from CHS if they use cannabis.

The compulsive showering and bathing associated with CHS is likely because hot temperatures help relieve its nausea and vomiting. The reasons why are unclear, but researchers have proposed that “hot bathing may act by correcting the cannabis-induced equilibrium of the thermoregulatory system of the hypothalamus.”

“The brain may react to changes in core body temperature due to the dose-dependent hypothermic effects of [THC],” offered a 2014 review. “Alternatively, the bathing behavior may be a result of direct CB1 receptor activation in the hypothalamus by [THC] or another active compound and may not necessarily be a response to changes in core body temperature,”

Why would cannabis cause CHS?

Photo via Flickr/ Kevin Galens

Scientists at Temple University have theories that activation of CB1 receptors, primarily by THC, could result in the inhibition of gastric acid secretion, along with the relaxation of the lower esophagus. Altered intestinal motility could result in visceral pain and inflammation, and delay gastric emptying, resulting in pain and nausea.

The paradox, of course, is that THC, when consumed heavily for a long period, could cause nausea via its effect on the gut, despite its anti-emetic properties in the brain.

It’s important to note that there is no proof and not even any real evidence that THC, CBD or other cannabinoids actually cause CHS. There are no substantiated results.

Many medical professionals are still skeptical.

Many medical professionals remain skeptical of the proposals and theories put forth by CHS researchers.

Authors of a 2006 Australian review criticized the original 2004 research that defined CHS. They said the 2004 study was flawed with poor study design, and that it was wrong in attributing increases in cannabis use to liberalized laws.

“Cannabis has been consumed for many centuries and is currently used by millions of people in many countries,” the authors wrote. “It is hard to believe that a distinctive syndrome caused by cannabis has never been noted before by users or clinicians.”

While a few studies have generated interest in this topic, there have been no epidemiologic studies associating marijuana use with CHS, according to one report which concludes there is no definitive link.

“This deficit is likely multifactorial due to the lack of formal diagnostic criteria for CHS, the relatively low prevalence of this syndrome, and the social stigma regarding marijuana use that discourages self-reporting.”

Could CHS be pesticide poisoning?

While man has used cannabis for thousands of years without CHS symptoms, the cannabis people use has recently undergone a big change: chemical pesticides.

Commercial marijuana farming operations are, by necessity, focused on production and the bottom line, so if an outbreak of pests such as spider mites occurs in a crop, they often use agents like azadirachtin. Azadirachtin is used in many products for spider mite and insect control, including the brand names Azamax, Azatrol, Aza-Sol, Align, Azatin, Turplex, and others.

According to those who subscribe to the theory that azadirachtin is responsible for the symptoms of CHS, “Cannabis without azadirachtin in it helps alleviate these symptoms to a great degree.”

“The CLEAN plants in the grow provided nothing but relief,” writes one grower. “Continued use of the clean cannabis made the CHS much more tolerable. I’ve continued to use clean cannabis and no longer suffer from CHS. The only time I have nausea and other CHS issues now are when I use too much cannabis from other growers, including dispensaries.”